Module:No globals

This module is subject to page protection. It is a highly visible module in use by a very large number of pages, or is substituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it is protected from editing.

This module causes an error if any nil global is read or if any global is written to, with the exception of arg. To use, add

require('Module:No globals')

to the top of the module using it. The arg variable is excluded because it is necessary for Scribunto's require function to work properly. (See the Scribunto source code here.)

local mt = getmetatable(_G) or {}
function mt.__index (t, k)
	if k ~= 'arg' then
		-- perf optimization here and below: do not load Module:TNT unless there is an error
		error(require('Module:TNT').format('I18n/No globals', 'err-read', tostring(k)), 2)
	end
	return nil
end
function mt.__newindex(t, k, v)
	if k ~= 'arg' then
		error(require('Module:TNT').format('I18n/No globals', 'err-write', tostring(k)), 2)
	end
	rawset(t, k, v)
end
setmetatable(_G, mt)